Seal blank



April 15, 1958 G. A. chossv SEAL BLANK Filed Feb. 10, 1953 I SEAL BLANKGeorge A. Crosby, Park Ridge, IiL, assignor to Signode Steel StrappingCompany, Chicago, Ill., a corporation of Delaware Application February10, 1953, Serial No. 336,678

' 1 Claim. (21. 24 23 The present invention relates to an improved sealblank for use in forming a seal or joint between overlapping ends ofmetallic strapping used for binding a bundle or like object.

Although a seal blank constructed according to the present invention hasa wider use, its principal utility and advantage is in that it can beformed into a joint in a position closer to the bundle than is usual andis particularly well adapted for use with magazine type tools andautomatic strapping machines, such as the type forming the subjectmatter of the copending applications of John H. Leslie II and George A.Crosby, Serial Nos. 48,448 and 134,526, filed respectively on September9, 1948, and December 22, 1949, now issued as Patent Nos. 2,707,429 and2,707,430, dated May 3, 1955, respectively, and assigned to the same'assignee as this application; also see patents numbered 2,594,397 and2,497,313 for instance. In automatic strapping machines the strapping isfed in an endwise direction from a coil and passed around a closed trackso as to encircle the bundle. As the free or leading end of thestrapping overlaps the standing portion, it is automatically grasped andheld. A seal blank which has been fed from a magazine and loaded intothe folding and deforming jaws of the sealing mechanism is brought intojoint-forming position against the strap and its flanges or wings arefolded about the overlapping strapping portion. This forms a sleeveencircling the strap so as to prevent movement of the overlappedportions of the strap with respect to each other exceptinglongitudinally. The machine then automatically pulls backwardly upon thestanding portion of the strap so as to shrink the loop of strappingabout the bundle and to tension the strapping material. Subsequently themachine automatically. deforms the seal blank and the enclosed portionof the strapping in a well known manner, usually by cutting parallelnotches at the side edges through the seal and strapping and thenbending the thus formed tabs downwardly so that they are angularlyoffset with respect to the plane of the main or undeformed portion ofthe strapping and seal.

In the operation of machines of the type generally set forth above andas more particularly described in the referred to copendingapplications, it will be recognized that after the seal is folded aboutthe overlapped ends of the quite loose strapping portions, and theloopof strapping is shrunk about the bundle by pulling lengthwise uponone end of the strapping, the standing portion of the strapping iscaused to slide for a considerable distance through the sleeve formed bythe seal. During this portion of the operation considerable difl'rlcultyis likely to be encountered because ordinarily the edges of the PatentedApr. 15, 1958 strapping are tightly pinched by the folded seal. Usuallyconsiderable friction is encountered as well as some cutting of theseal. Because of the heat generated by the friction, the speed ofoperation of the machine cycle is limited since experience indicatesthat care must be taken not to shrink the loop too rapidly about theobject being bound. Also under some conditions the friction thusgenerated may be sufiicient to drag the seal in an endwise directionsomewhat, thereby disturbing its proper position in the sealing jaws. 7

With hand operated magazine type tools much the same activity takesplace excepting that the strapping is passed around the bundle andordinarily much of the slack is taken up by hand before the tool takesover the final tensioning and sealing operations. a

The principal object of the present invention is to pro vide a novelseal blank which overcomes these objections.

An additional object is to provide a novel seal blank which is adaptedfor use with automatic, folding and sealing jaws which through normaloperation of the machine will have its tabs or wings folded aboutoverlapped portions of strapping so as to form a sleeve which does notproduce a high order of frictional engagement with the edges of thestrapping material.

Still another object is to obtain the above results while at the sametime providing an arrangement which enables the joint to be formed in aposition closer to the bundle than is customary.

Yet another object is to provide an improved seal blank having the abovedescribed characteristics, which can be manufactured at low cost.

Other objects and advantages of the present invention will becomeapparent from the following description of a preferred embodimentthereof which is illustrated in the accompanying drawings.

in the accompanying drawings, where similar characters of referencerefer to similar parts throughout the several views:

Figure 1 is a top view of a seal blank embodying the present invention;V

Fig. 2 is a perspective view thereof with the front edge of the viewcomprising a transverse medial section which may be considered as takeninthe direction of the arrows substantially along the line 22 of Fig. 1;

Fig. 3 is a view in transverse medial section of the seal shown in Figs.1 and 2, shown with the strapping and the folding jaws associatedtherewith at the beginning of a folding cycle; and

Figs. 4 to 6 are similar to Fig. 3 excepting that they show successivestages in the seal forming operation, with the completion of the foldingoperation being illustrated in Fig. 6.

In the drawings, overlapped strap portions to be sealed together areindicated by the numerals 10 and 12. The

, seal as a whole is indicated by the numeral 14 and is made up of thefollowing portions all integrally formed together from a piece of cut,folded and coined sheet metal of appropriate thickness. The seal has arectangular, flat, back or central portion 16 which is slightly widerthan the width of the strapping with which it is intended to be used.Along its side edges this central portion 16 is integrally joined byrounded corners 15 to a pair of wings 18 which are reverse complementsof each other. As supplied for use in the machine these wings divergeoutwardly somewhat so that their free ends are farther apart than arethe portions connected to the central back piece 16. This is done sothat the seal blank can approach the overlapped strap ends laterally andalso permits comparatively close nesting or staclc'ngof seals in themagazine of the strapping machine. A seal having the generalcharacteristics outlined above is well known and as pointed outpreviously usually occasions some pinching at the edges of the strappingwhen it is folded about the overlapped strap ends. This it has beenfound is because the metal of whichthe seal is formed tends to bend toosharply at the corners where the wings are joined to the-centralportion. Also, the folding jaws need to have overhanging lips at theirextreme ends for grasping the edges of the wings so as to limit theoutward movement of the blank when the jaws. start to be d the wingstoward each other,.and because of these lips the joint ust be rm in a Ps ion some di anc om the bundle o pr de the nece sary clearanc f th js.- hus i nr i cnt bu d e an when t e j i is formed upon a short face ofa bundle there may be more slack i e tra pin th n i esi a sa sr the jois formed.

Theseal blank of the present invention is provided on the inside withcoined grooves which extend longitudinally of the seal wings for thefull length of the seal blank at a position slightly outwardly of thecorners 15. The metal is thus weakened at this position by having itsthickness reduced .by a matter of a few thousandths of an inch whichaids in producing a greater degree of bending along the grooves 20 thanwould otherwise take place. In addition to .this, another set of coinedgrooves 22 are formedparallel to the grooves 20. Unlike grooves 20,however, the grooves 22 are formed into the exterior face of the sealblank in positions close to the free ends. Also the grooves 22 in thepresent example do not extend the full length of the seal but areconfined to about half this distance. They are centered, however, fromend to end so as to lie in the middle portion of the seal wings. Thesegrooves 22 are also formed by a coining operation so that the metal isreduced in thickness slightly thereby, while the inside surface of theseal blank remains smooth.

When a seal having these characteristics is loaded by the magazine of atool or automatic strapping machine into the folding jaws, it appearsmuch as illustrated in Fig. 3.

From an inspection of this figure of the drawing it will i be seen thatthe back of the seal is supported by a chair 24 and is positionedbetween a pair of folding jaws 26 which pivot about a pair of parallelaxes, one of which is indicated .at 28. '!The overlapped strap endsindicated at 10 and 12 are against the inside central portion of theseal blank or closely adjacent thereto, and at this time the loop formedby the strappinglO and,12 is very loose about the bundle to be bound.The ends of the folding jaws indicated at are comparatively sharp andengage the outer face of the seal wings at positions slightly outwardlybeyond thegrooves 22. Ordinarily where there are several sets of.folding jaws which operate together in side by side relationship withnotching jaws spaced between them onlyv some of these sets .(the centralset in the present instance) need to have the sharp tips or ends-asindicated at 30, the others having more rounded ends as indicated at 32.In any event, it is not necessary to provide any of the jaw ends withlips of the type previously mentioned as being customary.

When the folding jaws swing inwardly about the pivoting axes 28 to theposition indicated in Fig. 4, it will be seen that not only do they havean inward component but also a downward or backward component toward thechair 24 inasmuch as the pivoting axes 28 are located at positionsoutwardly of the ends 30 of the jaws. upon slight inward and downwardmovement of the jaws 26 the noses 30 thereof will snap into the grooves22 as indicated in Fig. 4. From this'it will be seen that the length andpositioning of the grooves 21. in a particular seal will depcnd 'uponthe width and number of sets of Therefore,

folding jaws having sharp ends which are employed in the tool with whichthe seal is to be used. Continued inward and downward movement of thefolding jaws therefore exerts a downward or backward force against thewings 18, tending to urge the seal blank downwardly or backwardlyagainst the chair 24. This causes a downward bending of the two edges ofthe central portion 16 of the seal blank so as to bend the edge portionsindicated at 34 away from the edges of the adjacent strap layer 12. Soonthereafter, with continjied inward and downward movement of the foldingjaws 26, the sharp noses 30 slide or rock out of the grooves 22, asindicated in Fig. 5, and at this portion of the cycle are producing adownward and inward action against the wings of the seal but are free toslide laterally over the outer surfaces of these wings. As this actioncontinues, so as to bring the inner faces of the wings against the toplayer of the strapping as indicated in Fig. 6, the formerly downwardlybent edges of the central portion indicated at 34 are bent upwardly orforwardly again into contact with the adjacent face of the strap layer12. The completely folded seal, therefore, appears as indicated in Fig.6, where it will be seen that the two layers of the strapping areclosely embraced between the central portion of the seal blank and thetwo wings and that the fold of the seal at the two edges of thestrapping does not quite touch the strapping edges. One layer of thestrapping, therefore, can be moved longitudinally at high speed in orderto shrink the loop about the handle to be bound and to apply a propertension to the strapping, after which the seal and strap edges may benotched in a conventional manner.

From the above it will be seen that the principal feature of the presentinvention is the provision of the grooves 22 to be caught by the nosesof the folding jaws so as to exert a strong downward component upon theit will be apparent that modifications and variations theretip,pivotally mounted folding and sealing jaws for forming a joint betweenoverlapping portions of metallic strapping, said blank having a fiatrectangular central portion with a width slightly greater than the widthof the strapping-with which the blank is to be used, and a pair ofrectangular wings joined by rounded corners to said central portionalong its side edges and extending diagonally outwardly therefrom,characterized by:the fact that each of said wings is formed withashallow, stock thinning groove on its inside surface extendingsubstantially the length of said wing parallel to the adjacent side edgeof said central portion andgspaced from the adjacent edge of saidcentral portion a distance slightly greater than two thicknesses of thestrapping rnaterial with which the seal blank is togbe used, each ofsaid wings adjace t the free edge thereof is formed with a jaw tipengaging groove on the external surface thereof, extendipg parallel tosaid free edge, and the inside and external eurfaces of said wingsexcept for said grooves are substanly smooth to perm nes n o a plura ityo s al blanks and the sliding of adjacent nested seal blanks relative toeach other, whereby when said wings are folded about the overlappingstrapping portions the sharp jaw tips temporarily engage in saidexternal surface grooves to impart a backward movement component to theinward folding movement of said wings to insure that the latter areproperly folded about the strapping portions without binding the edgesof the strapping portions between the central portion and the foldedwings of the seal blank.

References Cited in the file of this patent UNITED STATES PATENTSBirkenmaier Apr. 12, 1932 Birkenmaier et a1 Nov. 27, 1934 Childress Feb.18, 1941 Reiter Mar. 11, 1941 Crosby June 14, 1955 FOREIGN PATENTS GreatBritain Jan. 27, 1941 Great Britain May 16, 1951

